The long range goal of this research is the understanding of active transport across cell membranes. We have attempted to obtain direct evidence for the LIV-binding proteins in leucine transport by E. coli. Genetic techniques will be combined with biochemical approaches to identify, solubilize, and isolate membrane components of glycine and leucine transport systems. The chemical and physical properties of the binding proteins will be examined to learn something about the steps in membrane transport. The regulation of leucine transport will be examined using mutants defective in either synthesis or transport of leucine. Experiments of this type will provide the basis for studying transport systems of mammalian tissues. Since certain human diseases are defects in membrane transport, the major contribution of this proposed work with bacteria to the health of humans is that it should provide methods of study and approaches for determining the mechanism of transport in more complex tissues.